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Finding the Fourth Proportional to 689.36, 1,034.49 and 643.80

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Solution

The fourth proportional to 689.36, 1,034.49 and 643.80 is: 966.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    689.36 : 1,034.49 = 643.80 : x
  2. Step 2: Convert to fraction form
    689.36/1,034.49 = 643.80/x
  3. Step 3: Cross multiply
    689.36x = 1,034.49 × 643.80
  4. Step 4: Simplify right side
    689.36x = 666,004.66
  5. Step 5: Solve for x
    x = 666,004.66/689.36
  6. Step 6: Final answer
    x = 966.13

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.